Electrical resistance.



UNITED STATES PATENT oEiriCE.

CHARLES E. HAY, or iLEoiaD, AND HER-BERT w. SULLIVAN. 0E LoNijoN,EirGLamg.

ELECTRICAL RESISTANCE,

Specification of Letters Patent.

Patented Feb. 85 1916.

Application ined March 14, 1914. seriai No. s24,s95.

jects of the King of Great Britain, resid-v ing, respectively, atIlford, in the county of Essex', and at London, both in England, haveinvented certain new and useful Improvements in Electrical Resistances,ofwhich the follgwing is a specification.

*The 'object of the present invention is to construct` an improvedcompact electrical resistance for measureinents of precision withalternating currents, at high frequencies such as are used, for example,in wireless telephony and telegraphy Vin which measurement-s it isnecessary thattlie resistance units be non-reactive (that is to say,free from residual self-inductance or capacity effects) and that theresistance units may be readily adjusted to the high degree of ohmicaccuracy necessary in instruments of precision. It has alreadybeenproposed by several.

inventors to construct resistances freey from residual induetaiice orcapacity effects. For insta-nce, it has -beenproposed toconstruct acompensated resistance from Woven material, in which wires were to beusedl as the warpandjoined in series. In one arrangement a non-inductiveresistanceof dislc form is made by Winding one turn of a strip of suchmaterial onv a. former, then doubling the strip backen itself andwinding a turn in the opposite direction and repeating this prot Otherinventors have proposed to cons ruct compensated coils for comparativelylow resistances in which, asl ordinarily constructed, the self-inductionetl'ect usually preponderates, by employing sheet strip or ribbondoubled on itself, the contiguous parts being separated by a thin layer`or layers of insulating material, preferably of high specific inductivecapacity. The double stripithusA formed lisin son eases, for instance,'when an ordinary ridge coil is to be made, covered with insulatingmaterial and formed into a coil or wound on va bob- `bin so as not tooccupy a very large space. This coiliiig increases the capacity effectconsiderably and enables shorter and narrower sheet, strips or ribbon tobe used than would otherwise be required, or it enables thickerinsulating material, or insulating material of smaller specificinductive capacity, to be used. This resistance was toibo adjusted. i

necessary, in any ordinary manner, and thel compensation was to beelfectedb'y varying the proximity of the-ends of the parts,

or the character of the insulating material,`

or both. llt Awas, also. proposed to effect the compensation by slidingone end transversely over the other end, parallel to their own planes.Having made a number of coml pensated coils of such strip, it wasproposed to join aY number of them in multiple arc or parallel, in orderto obtain low resistance units or to arrange two or more of the coils inseries to produce moderate or large resistaiices. s

According to our invention we employ a multiple conductor consisting ofa number of wires arranged side-:by side in a plane and suitably'insulated from each other. A pair of these multiple conductors Ais laidup obliquely or transversely around a core ot insulating material, 'Vhenlaid up obliquely'-one layerv mayv be wound revcrsely toY the other.lVhile we have shown the layers of the multiple'- conduetors as laid upiii opposite directions,.such an arrange ment vis not necessary and,fromfan electrical point -of view, better results will be obtained ifthe conductors be laid up in the same direction. The tuf'o'layers thusform practically tubular conductors larranged eorieentrically. l'Vhenwound transversely at right angles to the core, the multiple conductormay be bent' back upon'itself, and the two layers may be woundvsimultaneously Y upon a core. The wires composing each layer are joinedin pa rallel,`aiid'oiic layer forms-thc go part o'f the circuit and theother the return art. .The distance between the go and the return partsor .layers is prefletermined` by calculation coi-ding to theresistaiicevalue of the unit required, which calculation is based oiiwellknown electrical laws and the distance differs with the nature ofthc metal or alloy, the gage of the wires and thc (li-electricv mediumsurrounding the-wires. The distance between thc 'wires' formingea'eh'inultiple conductor is governed iu all cases by the distanceseparating tlic"go and retin-u" layers. The number of wires forming theconductor in cach layer may or may not be equal in number or gage.

with a resistance constructed according( to ourfiiireiitiou thc relationof capacity' to iiiduetaiicc uniformly maintained adjustment withoutdisturbing the balance of capacity reactance andinductance react ance,Again this mode of construction enables us more readily to annul theresidual i inductance of ourresistance coils by reason of the increasedcapacity of conductors se designed.

Another advantage of our invention is that eddy currents are reduced toa minimum owing to the sub-division of the conductors, and circulatorycurrents within the unit of resistance are suppressed owing to the wiresforming the unit having the same electrical constants (resistance,capacity inductance and `leakance) The invention is illustrated in theaccom panying drawings, Ain which Figure l is a side elevation of aresistance made up of multiple conductors in the forni of a strand orwire rope and Fig. 2 is a cross section of the same. Fig. 3 is a plan ofa portion of a woven multiple conductor and Fig. 4 is a cross ctionthrough two layersofthe same. Fig. 5 is a cross section of a resistancein which the woven material shown in Figs. 3 and 4 is wound on abobbin'at right angles to the axis.

Figs. 1 and 2 show a resistance in which the two multiple conductors,each consisting of separate insulated wires, are woundv spirally arounda core 01 of cotton or other insulating material. 'One of these multipleconductors, for instance, the inner one, consisting of the Wires a, isthe go conductor, and the other, consisting of the wires al, is thereturn conductor. The wires a are so wound that there is a completetubular covering on the core c1, and the wires a1 are wound so thatthere is a complete tubular covering on the wires a. c2 is on outerprotecting sheath of insulating material. The

number of wires forming each multiple conductor, and their gage and thethickness or" their insulating covering depend upon the resistance ofthe unit to be constructed. The numberof wires in the two tubularcoverings and the gage of the wires inone covering may vary from that inthe other covering. The distance between the adjacent'wires a of the oneconductor vand of the adjacent wires ai of the other conductor dependsupon the distance apartof the concentric layers and is governed ashereinbefcre described.

A l0 ohm resistance coil constructed according to Figs. l and 2 may havethe tot lowing dimensions z-e-First layer-nine wires (Eure-ira) 9.2mils., standard double silk covered, 1125 ohms 'per yard. Second layertwenty one wires (Uurelial, 3.0 niils., standard singie silk covered'1135i ohms per yard. The diameter of the core is not iinportant so longas it cover .v with a ccntinuous layer o wires.

In Figs. 3 and fl, a, c, represent the insu lat-ed wires of the multipleconductor, which are joined in parallel, and t, present the weft made cisilk, cot-ten or the like. nstead of windinp the multiplie conductorobliquely in two iayers arcund core, as shown in Figs. l and. 2. we mayoid a strip upon itself and wind the two strips or layers simultaneouslyaround a cylindrical.. tube or bobbin ci and at ri gilt angles to theaxis of the bcbbin, as shown in Fig. 5. The one strip, A, will containthefgo wires a., and the other strip, A1,. the return wires al, thedistance between, adjacent wires in one strip and the di sta nce, .e sA., A1, being regulated liereinbeiore de scribed.

A 10 ohm resistance coil constructed from woven material having wirestcr the warp joined in parallel may have the ollowing dimensions z-Jlenwiresgage 6 rnils. (bare). The wire is weven in` such a 'way that thedistance between the wires forming the tape is greater than 3 mils., andthe distance between the go and return tape is 3 mils. Resistance-12.38chine per yard 'for Eureka. Another esaniple: Teri wires-w gage 9 mils.(bare). Elst-ance between tapeszl mils. Eistanee between. wires intapeznot less than mils. Resistance: 1.013 ohms per yard for Eureka.

It will be understood that in all the constructions, all the wires awill be connected together toform one terminal or end, and all the wiresai will be connected together to form the other terminal or end.

'What we claim is :w

1. An electrical resistance comprising two conductors each formed of aplurality ci' insulated wires placed side by .side and wound upon a coreof insulating material in two layers, the wires of each conductor beingin parallel, one layer forming the outgoing ccnductor and the otherlayer orir'ng the return conductor, the distance between adiacent wiresin each conductor being proportioned to the distance separating theductors, whereby reactionl due to indue tance is balanced by the counterreaction due to capacity.

2. An electrical resistance comprising two conducto-rs each formed of aplurality of insulated wires placed side by side, and wound obliquelyupon a core of insulating material in superposcd layers, the wires ofeach con ice tance separatingr the conductors, whereby reaction due toself' induotanee is balanced by the counter reaction due to capacity.

$5. An electrical resistance comprising two conductors each formed of aplurality of insulated wires placed side by Side7 and wound obliqnelyupon a core of insulating` material in .f-:uperposeil layers, the wire@of each Conductor being joined in parallel, one layer forming theoutgoing conductor and the other layer forming the return .conductor, v`hereby reaction due to self iinluetanee is balanced by the counterreaction (lue to oapaeitmv, the layers` being ineula'tetl troni eachother the distance between adjacent wires in eaeli vcoiuluctor beingproportioned to the lietanee separating the coinluctors.

1L. An electrical resistance comprising a multiplo conductor formed ofWoven uniterial7 having a warp ot conducting material,

the strands of which are connected in parallel, a weft of ibrousinsulating, material covering the conductors and spacing them apart,said multiple conductor being Wound upon a core, a second multipleconductor formed Qt' a woven material having a Warp composed ofconducting material the Strands of which are connected in parallel, aWett of fibrous, insulating material covering the con ductors andspacing theni apart, said Second multiple conductor being' Wound uponthe first mentioned multiple conductor and connected in seriestherewith.

In witness whereof We have hereunto Set our hands in presence ot' twowitnesses.

l CHARLES E. HAY.

HERBERT W. SULLIVAN. "itnessest WM. GniLNG, O. J. VORTH.

